Abstract

Air-broadened and N2-broadened halfwidths at room temperature for twenty-five transitions in the ν4 fundamental band of 12CH4 have been determined from IR absorption spectra recorded with a tunable diode laser spectrometer. Two tunable diode lasers operating in the 1250–1380-cm−1 region were used to obtain these data. Air-broadened halfwidths for twenty of these lines were also determined from additional spectra recorded at 0.01-cm−1 resolution with the Fourier transform spectrometer in the McMath solar telescope complex on Kitt Peak. The air-broadened halfwidths obtained from these two techniques are very consistent with agreement better than 3% in most cases.

© 1985 Optical Society of America

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References

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  1. D. E. Jennings, A. G. Robiette, “Determination of the ν4 Band Strength of 12CH4 from Diode Laser Line Strength Measurements,” J. Mol. Spectrosc. 94, 369 (1982).
    [CrossRef]
  2. M. A. H. Smith, C. P. Rinsland, B. Fridovich, K. Narahari Rao, “Intensities and Collision Broadening Parameters from Infrared Spectra,” in Molecular Spectroscopy: Modern Research, Vol. 3, K. Narahari Rao, Ed. (Academic, Orlando, 1985), Chap. 3.
  3. P. Varanasi, F. K. Ko, “Absorption by Self-broadened Rotational Lines in the ν4-Fundamental of 12CH4,” J. Quant. Spectrosc. Radiat. Transfer 25, 307 (1981).
    [CrossRef]
  4. P. Varanasi, L. P. Giver, F. P. J. Valero, “Thermal Infrared Lines of Methane Broadened by Nitrogen at Low Temperatures,” J. Quant. Spectrosc. Radiat. Transfer 30, 481 (1983).
    [CrossRef]
  5. V. Malathy Devi, B. Fridovich, G. D. Jones, D. G. S. Snyder, A. Neuendorffer, “Temperature Dependence of the Widths of N2-broadened Lines of the ν3 Band of 14N16O2,” Appl. Opt. 21, 1537 (1982).
    [CrossRef]
  6. B. Fridovich, V. Malathy Devi, P. P. Das, “Convolution of a Doppler Line by a Gaussian Instrument Function,” J. Mol. Spectrosc. 81, 269 (1980).
    [CrossRef]
  7. E. E. Whiting, “An Empirical Approximation to the Voigt Profile,” J. Quant. Spectrosc. Radiat. Transfer 8, 1379 (1968).
    [CrossRef]
  8. J. J. Olivero, R. L. Longbothum, “Empirical Fits to the Voigt Line Width: A Brief Review,” J. Quant. Spectrosc. Radiat. Transfer 17, 233 (1977).
    [CrossRef]
  9. B. Fridovich, “Correcting Measured Line Halfwidths,” J. Mol. Spectrosc. 105, 53 (1984).
    [CrossRef]
  10. C. P. Rinsland, D. C. Benner, D. J. Richardson, R. A. Toth, “Absolute Intensity Measurements of the (1110)II ← 0000 Band of 12C16O2 at 5.2 μm,” Appl. Opt. 22, 3805 (1983).
    [CrossRef] [PubMed]
  11. L. S. Rothman et al., “AFGL Atmospheric Absorption Line Parameters Compilation: 1982 Edition,” Appl. Opt. 22, 2247 (1983).
    [CrossRef] [PubMed]

1984 (1)

B. Fridovich, “Correcting Measured Line Halfwidths,” J. Mol. Spectrosc. 105, 53 (1984).
[CrossRef]

1983 (3)

1982 (2)

D. E. Jennings, A. G. Robiette, “Determination of the ν4 Band Strength of 12CH4 from Diode Laser Line Strength Measurements,” J. Mol. Spectrosc. 94, 369 (1982).
[CrossRef]

V. Malathy Devi, B. Fridovich, G. D. Jones, D. G. S. Snyder, A. Neuendorffer, “Temperature Dependence of the Widths of N2-broadened Lines of the ν3 Band of 14N16O2,” Appl. Opt. 21, 1537 (1982).
[CrossRef]

1981 (1)

P. Varanasi, F. K. Ko, “Absorption by Self-broadened Rotational Lines in the ν4-Fundamental of 12CH4,” J. Quant. Spectrosc. Radiat. Transfer 25, 307 (1981).
[CrossRef]

1980 (1)

B. Fridovich, V. Malathy Devi, P. P. Das, “Convolution of a Doppler Line by a Gaussian Instrument Function,” J. Mol. Spectrosc. 81, 269 (1980).
[CrossRef]

1977 (1)

J. J. Olivero, R. L. Longbothum, “Empirical Fits to the Voigt Line Width: A Brief Review,” J. Quant. Spectrosc. Radiat. Transfer 17, 233 (1977).
[CrossRef]

1968 (1)

E. E. Whiting, “An Empirical Approximation to the Voigt Profile,” J. Quant. Spectrosc. Radiat. Transfer 8, 1379 (1968).
[CrossRef]

Benner, D. C.

Das, P. P.

B. Fridovich, V. Malathy Devi, P. P. Das, “Convolution of a Doppler Line by a Gaussian Instrument Function,” J. Mol. Spectrosc. 81, 269 (1980).
[CrossRef]

Fridovich, B.

B. Fridovich, “Correcting Measured Line Halfwidths,” J. Mol. Spectrosc. 105, 53 (1984).
[CrossRef]

V. Malathy Devi, B. Fridovich, G. D. Jones, D. G. S. Snyder, A. Neuendorffer, “Temperature Dependence of the Widths of N2-broadened Lines of the ν3 Band of 14N16O2,” Appl. Opt. 21, 1537 (1982).
[CrossRef]

B. Fridovich, V. Malathy Devi, P. P. Das, “Convolution of a Doppler Line by a Gaussian Instrument Function,” J. Mol. Spectrosc. 81, 269 (1980).
[CrossRef]

M. A. H. Smith, C. P. Rinsland, B. Fridovich, K. Narahari Rao, “Intensities and Collision Broadening Parameters from Infrared Spectra,” in Molecular Spectroscopy: Modern Research, Vol. 3, K. Narahari Rao, Ed. (Academic, Orlando, 1985), Chap. 3.

Giver, L. P.

P. Varanasi, L. P. Giver, F. P. J. Valero, “Thermal Infrared Lines of Methane Broadened by Nitrogen at Low Temperatures,” J. Quant. Spectrosc. Radiat. Transfer 30, 481 (1983).
[CrossRef]

Jennings, D. E.

D. E. Jennings, A. G. Robiette, “Determination of the ν4 Band Strength of 12CH4 from Diode Laser Line Strength Measurements,” J. Mol. Spectrosc. 94, 369 (1982).
[CrossRef]

Jones, G. D.

Ko, F. K.

P. Varanasi, F. K. Ko, “Absorption by Self-broadened Rotational Lines in the ν4-Fundamental of 12CH4,” J. Quant. Spectrosc. Radiat. Transfer 25, 307 (1981).
[CrossRef]

Longbothum, R. L.

J. J. Olivero, R. L. Longbothum, “Empirical Fits to the Voigt Line Width: A Brief Review,” J. Quant. Spectrosc. Radiat. Transfer 17, 233 (1977).
[CrossRef]

Malathy Devi, V.

V. Malathy Devi, B. Fridovich, G. D. Jones, D. G. S. Snyder, A. Neuendorffer, “Temperature Dependence of the Widths of N2-broadened Lines of the ν3 Band of 14N16O2,” Appl. Opt. 21, 1537 (1982).
[CrossRef]

B. Fridovich, V. Malathy Devi, P. P. Das, “Convolution of a Doppler Line by a Gaussian Instrument Function,” J. Mol. Spectrosc. 81, 269 (1980).
[CrossRef]

Narahari Rao, K.

M. A. H. Smith, C. P. Rinsland, B. Fridovich, K. Narahari Rao, “Intensities and Collision Broadening Parameters from Infrared Spectra,” in Molecular Spectroscopy: Modern Research, Vol. 3, K. Narahari Rao, Ed. (Academic, Orlando, 1985), Chap. 3.

Neuendorffer, A.

Olivero, J. J.

J. J. Olivero, R. L. Longbothum, “Empirical Fits to the Voigt Line Width: A Brief Review,” J. Quant. Spectrosc. Radiat. Transfer 17, 233 (1977).
[CrossRef]

Richardson, D. J.

Rinsland, C. P.

C. P. Rinsland, D. C. Benner, D. J. Richardson, R. A. Toth, “Absolute Intensity Measurements of the (1110)II ← 0000 Band of 12C16O2 at 5.2 μm,” Appl. Opt. 22, 3805 (1983).
[CrossRef] [PubMed]

M. A. H. Smith, C. P. Rinsland, B. Fridovich, K. Narahari Rao, “Intensities and Collision Broadening Parameters from Infrared Spectra,” in Molecular Spectroscopy: Modern Research, Vol. 3, K. Narahari Rao, Ed. (Academic, Orlando, 1985), Chap. 3.

Robiette, A. G.

D. E. Jennings, A. G. Robiette, “Determination of the ν4 Band Strength of 12CH4 from Diode Laser Line Strength Measurements,” J. Mol. Spectrosc. 94, 369 (1982).
[CrossRef]

Rothman, L. S.

Smith, M. A. H.

M. A. H. Smith, C. P. Rinsland, B. Fridovich, K. Narahari Rao, “Intensities and Collision Broadening Parameters from Infrared Spectra,” in Molecular Spectroscopy: Modern Research, Vol. 3, K. Narahari Rao, Ed. (Academic, Orlando, 1985), Chap. 3.

Snyder, D. G. S.

Toth, R. A.

Valero, F. P. J.

P. Varanasi, L. P. Giver, F. P. J. Valero, “Thermal Infrared Lines of Methane Broadened by Nitrogen at Low Temperatures,” J. Quant. Spectrosc. Radiat. Transfer 30, 481 (1983).
[CrossRef]

Varanasi, P.

P. Varanasi, L. P. Giver, F. P. J. Valero, “Thermal Infrared Lines of Methane Broadened by Nitrogen at Low Temperatures,” J. Quant. Spectrosc. Radiat. Transfer 30, 481 (1983).
[CrossRef]

P. Varanasi, F. K. Ko, “Absorption by Self-broadened Rotational Lines in the ν4-Fundamental of 12CH4,” J. Quant. Spectrosc. Radiat. Transfer 25, 307 (1981).
[CrossRef]

Whiting, E. E.

E. E. Whiting, “An Empirical Approximation to the Voigt Profile,” J. Quant. Spectrosc. Radiat. Transfer 8, 1379 (1968).
[CrossRef]

Appl. Opt. (3)

J. Mol. Spectrosc. (3)

B. Fridovich, V. Malathy Devi, P. P. Das, “Convolution of a Doppler Line by a Gaussian Instrument Function,” J. Mol. Spectrosc. 81, 269 (1980).
[CrossRef]

D. E. Jennings, A. G. Robiette, “Determination of the ν4 Band Strength of 12CH4 from Diode Laser Line Strength Measurements,” J. Mol. Spectrosc. 94, 369 (1982).
[CrossRef]

B. Fridovich, “Correcting Measured Line Halfwidths,” J. Mol. Spectrosc. 105, 53 (1984).
[CrossRef]

J. Quant. Spectrosc. Radiat. Transfer (4)

P. Varanasi, F. K. Ko, “Absorption by Self-broadened Rotational Lines in the ν4-Fundamental of 12CH4,” J. Quant. Spectrosc. Radiat. Transfer 25, 307 (1981).
[CrossRef]

P. Varanasi, L. P. Giver, F. P. J. Valero, “Thermal Infrared Lines of Methane Broadened by Nitrogen at Low Temperatures,” J. Quant. Spectrosc. Radiat. Transfer 30, 481 (1983).
[CrossRef]

E. E. Whiting, “An Empirical Approximation to the Voigt Profile,” J. Quant. Spectrosc. Radiat. Transfer 8, 1379 (1968).
[CrossRef]

J. J. Olivero, R. L. Longbothum, “Empirical Fits to the Voigt Line Width: A Brief Review,” J. Quant. Spectrosc. Radiat. Transfer 17, 233 (1977).
[CrossRef]

Other (1)

M. A. H. Smith, C. P. Rinsland, B. Fridovich, K. Narahari Rao, “Intensities and Collision Broadening Parameters from Infrared Spectra,” in Molecular Spectroscopy: Modern Research, Vol. 3, K. Narahari Rao, Ed. (Academic, Orlando, 1985), Chap. 3.

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Figures (2)

Fig. 1
Fig. 1

Tunable diode laser scans in the region of two 12CH4 lines at 1322 cm−1. Ge etalon fringes obtained simultaneously with the lowest scan are also shown.

Fig. 2
Fig. 2

Comparison between a FTS laboratory spectrum of methane and a least-squares best fit to the data. The laboratory spectrum (lower plot) was obtained with 350.5 Torr of 1.005% CH4 in dry air in a 25-cm absorption path at 25.2°C. The differences (observed–calculated) are shown in the upper panel and are expressed as a percentage of the peak intensity in the fitted region. The standard deviation of the fit is 0.139%.

Tables (1)

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Table I Air- and N2-Broadened Halfwidths (cm−1 atm−1) in the ν4 Band of 12CH4 at 296 K

Equations (2)

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b L = b V { 7 . 7254 6 . 7254 [ 1 + 0 . 3195 ( b D b V ) 2 ] 1 / 2 } .
b L 0 = b L / P ,

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